bug(front50): add GroovyJson dependency

Test was failing without it. The test code that uses it was added back when we were in Groovy 2, after the upgrade to Groovy 3 I believe it's required as an explicit dependency.

orca-front50/orca-front50.gradle

@@ -39,6 +39,7 @@ dependencies {
   testImplementation(project(":orca-pipelinetemplate"))
   testImplementation("com.github.ben-manes.caffeine:guava")
   testRuntimeOnly("net.bytebuddy:byte-buddy")
+  testImplementation("org.codehaus.groovy:groovy-json")
 }
 
 sourceSets {